Q. Enclosed is a sweet potato souffle' recipe I've used for 12 years. I've often frozen the leftovers and, although I have none from the original vintage, I've eaten it after it has hibernated one year in the freezer. Is this dangerous? The texture and taste is satisfactory, though not of guest-quality.
A. With spoilage, pathogens (such as salmonella) and preserved foods, there are no absolutes. Pathogens, fortunately, are picky about their environment. Most find the freezer extremely inhospitable; few survive the temperatures more than a week or two. Thus, even if a food is moderately contaminated, its bacterial population diminishes the longer it remains frozen. There are some organisms that survive the cold and even grow, but they only result in a flavor change.
In addition to the temperature, other barriers are the recipe's high sugar concentration (a 25 percent sugar solution, which most bacteria find inhospitable, though yeasts are not too bothered) and the baking process, which removes almost all organisms.
Here's the recipe, which freezes well because of its low-water, high-sugar content: SWEET POTATO SOUFFLE (6 to 8 servings)
5 cups mashed sweet potatoes
1 cup sugar
1/2 teaspoon salt
2 eggs, slightly beaten
1 teaspoon vanilla extract
8 tablespoons butter plus extra for casserole
1/2 cup milk
1 cup brown sugar
1/3 cup all-purpose flour
1 cup chopped pecans (or other nuts)
Bake 3 sweet potatoes in a 350-degree oven until soft. Remove and peel. Mash with a fork and measure. In a mixing bowl, blend the potato mash, sugar, salt, eggs, extract, 3 tablespoons butter and milk until smooth. Pour into a greased casserole.
In another mixing bowl, rub brown sugar, flour, 5 tablespoons butter and nuts together between your hands. Sprinkle over the casserole. Bake in a 350-degree oven for 35 minutes.